TRACHEATES 199 



good deal to be desired. It would often happen, for 

 instance, that an insect would fly from one male flower 

 to another, and not visit a female catkin until much 

 later. In this way a great deal of pollen would be 

 lost, and so we can understand that a different method 

 would lead to better results. We still find in the 

 poplars, which have the same kind of catkin-blooms, 

 a pistil with a stigma and germ suddenly appearing 

 as an abnormality in the middle of a male flower ; this 

 union of male and female in one flower is called 

 hermaphrodism. These hermaphrodites were pre- 

 served by natural selection, as they had a great 

 advantage in the conveyance of pollen from flower 

 to flower. An insect that covered itself with pollen 

 dust in one flower found a pistil in the next one on 

 which it could brush the dust, and did not fail by going 

 exclusively from one male flower to another. Hence 

 the hermaphroditic flowers increased, and a struggle 

 sprang up amongst them for the visitors, those being 

 most favoured that were most attractive to the insects. 

 The chief means was, of course, the honey on which 

 the insects fed ; and those flowers had an additional 

 advantage that drew attention by their conspicuous 

 colours, and so invited the insects from afar. This 

 was the origin of almost all our actual beautifully- 

 coloured and marvellously-shaped flowers. Nature does 

 not revel in a superfluous wealth of colouring ; this has 

 only been developed for the sake of the insects, as no 

 plant of this kind can reproduce unless it is visited by 

 insects. A second source of attraction was provided 

 in the scent, which, of course, was especially useful 



